Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2007 Nov;50(11):2239-44.
doi: 10.1007/s00125-007-0803-0. Epub 2007 Sep 13.

Relationship between glycated haemoglobin levels and mean glucose levels over time

D M Nathan  1 , H Turgeon, S Regan
Affiliations

Relationship between glycated haemoglobin levels and mean glucose levels over time

D M Nathan et al. Diabetologia. 2007 Nov.

Abstract

Aims/hypothesis: HbA(1c), expressed as the percentage of adult haemoglobin that is glycated, is the most widely used measure of chronic glycaemia. Achieving near-normal HbA(1c) levels has been shown to reduce long-term complications and the HbA(1c) assay is recommended to determine whether treatment is adequate and to guide adjustments. However, daily adjustments of therapy are guided by capillary glucose levels (mmol/l). We determined the relationship between an accurate measure of mean glucose levels over time and the HbA(1c) level, and whether HbA(1c) can be expressed in the same units as self-monitoring results.

Methods: Twenty-two participants with diabetes and three non-diabetic participants were included in this longitudinal observational study. Mean glucose levels were measured by continuous glucose monitoring (CGM), which measures interstitial glucose levels every 5 min, for 12 weeks. Capillary measurements were obtained four times per day to confirm the accuracy of CGM. HbA(1c) was measured at baseline and every 4 weeks.

Results: The HbA(1c) results at weeks 8 and 12 correlated strongly (r = 0.90) with the CGM results during the preceding 8 and 12 weeks. A curvilinear (exponential) relationship and a linear regression captured the relationship with similarly high correlations, which allowed transformation of HbA(1c) values to a calculated mean glucose level.

Conclusions and interpretation: HbA(1c) correlates closely with a complete measure of average glycaemia over the preceding 8-12 weeks. The translation of HbA(1c) to an average glucose level for reporting and management purposes is feasible.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Relationship between HbA1c at month 3 and mean glucose level calculated from CGM during 12 previous weeks according to (a) linear regression mean CGM = HbA1c × 1.75–3.81 (r = 0.89, p < 0.001), and (b) the exponential mean CGM = 1.28HbA1c + 0.000136exp(HbA1c)–0.92 (r = 0.89, p < 0.001). Continuous line, fitted values; diamonds, observed values
See this image and copyright information in PMC

Comment in

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Saudek CD, Derr RL, Kalyani RR. Assessing glycemia in diabetes using self-monitoring blood glucose and hemoglobin A1c. JAMA. 2006;295:1688–1697. doi: 10.1001/jama.295.14.1688. - DOI - PubMed
    1. American Diabetes Association Standards of medical care of diabetes. Diabetes Care. 2007;30(Suppl 1):S4–S41. doi: 10.2337/dc07-S004. - DOI - PubMed
    1. Goldstein DE, Little R, Lorenz RA, et al. Tests of glycemia in diabetes. Diabetes Care. 2004;27:1761–1773. doi: 10.2337/diacare.27.7.1761. - DOI - PubMed
    1. Koenig RJ, Peterson CM, Jones RL, Saudek C, Lehrman M, Cerami A. Correlation of glucose regulation and hemoglobin A1c in diabetes mellitus. N Engl J Med. 1976;295:417–420. doi: 10.1056/NEJM197608192950804. - DOI - PubMed
    1. Koenig RJ, Peterson CM, Kilo C, Cerami A, Williamson JR. Hemoglobin A1c as an indicator of the degree of glucose intolerance in diabetes. Diabetes. 1976;24:230–232. doi: 10.2337/diab.25.3.230. - DOI - PubMed

Publication types